A laparoscopic surgery or thoracoscopic surgery is a method (hereinafter referred to as endoscopic surgery in some cases), of which a state in an abdominal cavity or chest cavity is reproduced on a video screen through a laparoscope or thoracoscope without opening the abdominal cavity, and the surgery is carried out using a special instrument while the screen is watched. In an endoscopic surgery, the surgery is carried out only by opening a plurality of small holes of approximately 5 to 10 mm in the abdomen or chest. In the laparoscopic surgery or thoracoscopic surgery, since wounds are small as above, pain after the surgery is less and since the wounds become substantially invisible, it has an esthetic merit. Also, duration of hospitalization can be short and rehabilitation into society is early. Under these circumstances, “NOTES (Natural Orifice Transluminal Endoscopic Surgery)” has drawn attention, and application to some diseases have been tried. According to the NOTES, a small hole is opened in a vaginal wall, intestinal wall, esophagus wall, gastric wall and the like through a vagina, rectum or mouth, an endoscope is inserted into a body cavity through the hole and an affected part in the body cavity can be treated through a vagina, rectum or mouth, for example. This surgery is expected to lead to alleviation of pain and cicatrix and drastic reduction of time required for recovery since ablation on the body surface can be minimized or eliminated.
However, in such endoscopic surgeries, a field of view of the endoscope is small and moreover, an intracorporeal tissue other than a treatment target interrupts the field of view of the endoscope and a treatment site, which might obstruct the treatment and incur prolongation of the entire operation time. Methods to prevent such interruption of the field of view or treatment site have been proposed.
For example, Patent Document 1 discloses a medical grasping tool that grasps an intracorporeal tissue such as mucosa at endoscopic demucosation and the like. This medical grasping tool is provided with a pair of grasping members for grasping an intracorporeal tissue and a connecting member for connecting the pair of grasping members. As grasping means, a clip provided with opposing claws, a ring or elastic band capable of reducing an opening diameter and tying the intracorporeal tissue, a sucker for sucking the organ or tissue by a negative pressure, a mesh bag or basket that can wrap an organ or tissue, a needle provided with a mechanism that is pierced into the intracorporeal tissue and prevents removal after that and the like are exemplified.    Patent Document 1: Japanese Patent Laid-Open No. 2005-103107
However, this medical grasping tool is used for holding a relatively light-weight target such as an ablated mucosa and the like and not intended to be used for holding an intracorporeal tissue such as a digestive tract that is relatively heavy and easily moves in an abdominal cavity or chest cavity. Also, since the grasping members are fixed to both ends of the connecting member, if the grasping tool is to be re-mounted at another spot or a different type of grasping means is required, the both ends of the medical grasping tool grasping the intracorporeal tissue should be removed and have to grasp the intracorporeal tissue again.